Standard galvanic cells usually produce an open circuit voltage of about 1.5 volts. When a higher voltage is required, it is customary to combine a multiplicity of these cells to form a battery having a required voltage. The cells are usually disposed in a container and connected in series with external terminals attached to the container and making contact with the cells. Therefore a 9-volt battery, commonly used in portable devices, would contain six 1.5 volt cells connected in series.
The individual cells within the multiple cell battery conventionally may be connected electrically by soldering or welding leads to the appropriate cell terminals. Soldering or welding the connections is a costly step, however, in assembling the battery. If the soldering or welding is done manually, then consistent quality connections may be hard to achieve. Also, if the batteries are subjected to severe shock and/or vibration, either in shipment or in usage, the soldered joints may be damaged or sometimes completely destroyed.
Another more recent type of multiple cell battery has eliminated the necessity for soldered or welded connections to electrically connect the cells. The battery utilizes pressure contact conductive strips to achieve proper intercell electrical connection. These strips are usually held in place by spring means which provide the necessary pressure to insure proper electrical contact between the individual cells and the strips.
Another problem with conventional multiple cell batteries is the possible leakage of corrosive exudate from the individual cells. In a confined container, any exudate could be contained in the container and prevent any environmental problem if the exudate poses a hazard. For example, electrolyte in various cells could escape to the environment under extreme operating conditions, such as when the cells are overly discharged.
U.S. Pat. No. 4,547,438 describes a battery assembly which comprises several gas depolarizable electrochemical cells, e.g., metal/air cells, stacked electrically in series along a first dimension. Each cell has first and second electrodes of opposite polarities. The battery assembly also comprises a housing for containing the stack of cells. The housing includes a structure for ventilating the interior of the housing and further includes first and second opposite end walls which lie perpendicular to the first dimension. The stack of cells is arranged within the housing with the first electrode of the initial cell of the stack facing the first wall and the second electrode of the final cell of the stack facing the second wall. The battery assembly further includes first and second electrically conductive connectors disposed within the housing. The first connector has a first end electrically coupled to the first electrode of the initial cell and a second end disposed adjacent the first wall. The second connector has a first end electrically coupled to the second electrode of the final cell and a second end also disposed adjacent the first wall. The battery assembly further comprises first and second terminals which are electrically coupled to the first and second connectors, respectively, and extend through the first wall to the exterior of the housing.
It is an object of the present invention to provide a multiple cell battery that is easy to assemble and that makes maximum use of the internal volume of the battery housing to accommodate cylindrical cells.
It is another object of the present invention to provide a multiple cell battery that uses pressure contact means for connecting a plurality of cells in series and to the outside terminals on the cells' housing.
It is another object of the present invention to provide a multiple cell battery that is suitable for connecting in series a plurality of depolarized cells.
It is another object of the present invention to provide a multiple cell battery that is easy to assembly and cost effective to produce.
Further objects, aspects and advantages of the invention will become apparent from the following detailed description and accompanying drawings.